Spiderwheels: eyes...

I have been putting a lot of thought into how to make the head of my spider and finally settled on a simple proximity sensor from SparkFun with two degrees of freedom. It is always good to start with a proof of concept and so I wired it up to my breadboard sanguino. I basically made it pan until it finds an obstacle and then nod. Here is a video:



Here is the source code:

#include <Servo.h> 
Servo zServo; //rotates about z
Servo xServo; //rotates about x

float zPos = 90; //keeps track of position. 90 degrees is resting.
float xPos = 90; //keeps track of position. 90 degrees is resting.

int milisecondsBetween = 20; 
int vMax = 300;

int sensorPin = 0;    // select the input pin for the potentiometer
int sensorValue = 0;  // variable to store the value coming from the sensor

void setup() {
  zServo.attach(13);  // attaches zServo object to pin 13 
  xServo.attach(12);  // attaches xServo object to pin 12 
  Serial.begin(19200);
}
void loop() {
  goLeft();
  goRight();
}
void goLeft(){
  float z = zPos;
  sensorValue = analogRead(sensorPin); 
  while(sensorValue < vMax && z > 50){
    z -= 10;
    moveTo(xPos, z);
    sensorValue = analogRead(sensorPin); 
  }
  if(sensorValue >= vMax){
    sayHi();
    printV(sensorValue);
  }
}
void goRight(){
  float z = zPos;
  sensorValue = analogRead(sensorPin); 
  while(sensorValue < vMax && z < 130){
    z += 10;
    moveTo(xPos, z);
    sensorValue = analogRead(sensorPin); 
  }
  if(sensorValue >= vMax){
    sayHi();
    printV(sensorValue);
  }
}
void printV(int v){
  Serial.print("v: ");
  Serial.print(v);   
  Serial.print("\r\n");  
}
void sayHi(){
  moveTo(90, zPos);
  moveTo(110, zPos);
  moveTo(90, zPos);
}
void moveTo(float x, float z){
  while(xPos != x|| zPos != z){
    if(xPos > x){
      xPos -= 1;
    }
    else if(xPos < x){
      xPos += 1;
    }
    if(zPos > z){

      zPos -= 1;
    }
    else if(zPos < z){
      zPos += 1;
    }
    zServo.write(zPos);
    xServo.write(xPos);
    delay(milisecondsBetween);
  }
}